The Study Of Variable-Speed Constant-Frequency Double-fed Wind Power Generation System

At present, the energy of mineral substance is the chief consumption energy, but with attachment importance to energy source scarcity and environment pollution, the renewable sources of energy has been gotten more attention than before. The wind electric power, which is one of the important pollution-free renewable sources of energy, is developed dramatically all over the world. As the best technical scheme, AC excited generator is used for wind-energy generation with variable-speed and constant-frequency widely. The programmer is studied mainly in wind-energy generation, because it can operate in large range of speed and with the best utilization factor of wind-energy.First, based on double-fed induction generator (DFIG) fundamental equation, the equivalent circuit and internal power relationship are analyzed in this dissertation, which establishes the theoretical base for study. Then simulation models of generator under grid-connection based on the synchronous revolution coordinate system are built from mathematics equations. With the analysis of energy converter and control strategy of the system, the power system voltage oriented vector control and the stator flux oriented vector control are used respectively in the grid side and the rotor side converter. The variable speed constant frequency and decoupling the active and reactive power control are implemented by modulating the rotor current. The modulation results indicate that the system has good dynamic power decoupling performance. Second, according to the basic theoretical of electromagnetic and combining the finite element method(FEM) with external circuit, a mathematical model of the double-fed induction generator is established in this dissertation. Generator under grid-connection characteristic curve at sub-synchronization speeds and change from sub-synchronization speed to sup-synchronization speed are calculated. The harmonic of the stator and rotor currents are analyzed. Theoretical approach together with experimental results confirms the validity of the proposed method. These calculations and experiments can provide some theoretical reference for improving the net power quality and electromagnetic properties of wind-power generators. Finally, the variable-speed constant-frequency (VSCF) wind power generator excited control system is designed by using TMS320LF2407A as the core chip which fit the motor control and The IPM as power converter. The signal detection and treating circuit and optoelectronic isolator circuit are also designed in this system.